Attachment for road grader



y 1957 c. T. MATHERS 3,330,365

ATTACHMENT FOR ROAD GRADER Filed Oct. 14, 1965 v 2 Sheets-Sheet l INVENTOR. B CHARLES T. MATHERS ATTORNEY July 11, 1967 Filed Oct. 14, 1965 c. T. MATH ERS 3,330,365

ATTACHMENT FOR ROAD GRADER 2 Sheets-Sheet 2 W In Q o 0 E 30 v k N :3) O o BI L0 /T, 9.

V R u 3 I to f q' i Q 0 NI 0 w. ll (T1 2 "R R1: 94 v o & INVENTOR. Q) N CHARLES T. MATHERS BY LL k ATTORNEY United States Patent 3,330,365 ATTACHMENT FOR ROAD GRADER Charles T. Mathers, Fresno, Calif. (4286 S. Del Rey Ave., Del Rey, Calif. 93616) Filed Oct. 14, 1965, Ser. No. 497,604 12 Claims. (Cl. 172-548) This application is a continuation-in-part of application Ser. No. 300,121, filed July 29, 1963, which is a continuation-in-part of application Ser. No. 103,025, filed Apr. 14, 1961, both now abandoned. The present invention relates to and attachment for motorized road graders so that the combination can be used for reworking oil cake pavement in a fast and efiicient manner. Also, the combination can be used for sub-base compaction, blending, the compaction of laid material, and for planing, filling, and compacting voids when refinishing a road. Further, the device can be used for planing the washboard from an oil cake road.

The prior art does not show or teach the construction of a machine unit which will do the work of the present invention. The prior art requires the use of two or more independent pieces of equipment to do the work which the present combination does by means of a single integrated piece of equipment. To rework an oil cake pavement, the prior art required that the road be scarified first, then that a heavy grid roller or similar device having a generally continuous circle type of operating surface be passed several times over the scarified material to further break the cake into small pieces, then the grader windrowed the material and, after the application of new oil, the grader made several passes over the material mixing it and finally spreading it. The prior art devices such as a grid roller or devices having numerous small teeth have generally relied on ground pressure to break the cake and the like. The present device eliminates much of this prior art work because in many instances the step of scarifying can be eliminated or done by large teeth of the present attachment, wherein impact, not down pressure, is emphasized as the operative force. The reducing of the oil cake to the desired size is done with fewer passes of this new combination than would be required with a grid roller or the like, and the new oil may be added and mixed Without Windrowing and, even if windrowed, the mixing is done and the material spread in fewer passes of the grader and its new attachment.

By comparison of the prior art devices and processes, it will be seen that some of the objects of the present invention are the devising of a simple attachment to a road grader which will enable the combination of the graders blade and the attachment to impact, cut, crush, size, and compact various road materials, old oil cake for instance, but, also, various rocks; to devise an attachment to a grader blade so that the combination will rapidly mix, blend, spread, and compact road materials; which will plane and finish a road surface; and which can be used on old road surfaces to remove washboard and other irregularities.

The above mentioned defects of the prior art are remedied and these objects achieved by a construction in which a heavy, free rolling, cylindrical member is carried in a frame which is detachably secured to and in front of the blade of a road grader. The outside diameter of the cylindrical member is about the width of the blade, and the length of the member may be six feet or more depending on the design and powering of the grader to handle a longer and heavier attachment. The length of the attachment would not be greater than the blade length as the blade and its face cooperate with the attachment in its operation. The attachment is secured to the graders blade so that the axis of the cylindrical member is parallel to the elongation of the blade, and the periphery of the member Patented July 11, 1967 is spaced about half the distance of its radius from the front face of the blade and about the same distance below the lower edge of the blade. The cylindrical member is composed of a large diameter tube having a stub shaft at each end journalled in the frame, and spiral splines on the face thereof. A series of toothed rings are coaxial of, circumjacent, and snug on the tube, or arbor, and the splines. For teeth, each of the rings has a plurality of large, circumferentially spaced scallops coextensive peripherally of the ring to form cutting edges with each edge extending peripherally of the ring, and, transverse and interjacent the cutting edges, hoe edges double the number of cutting edges. Each of the edges, cutting and hoe, is backed by a wedge shaped base, and all the bases merge to form a continuous base ring.

The scallop edges may be called slicing edges and each scallop may be called a cutter or slicer. This is because the edge extends in its direction of movement into, thru, and across the material being operated on.

Also, for this same reasoning the edges which extend axially of the ring are called hoe edges or crusher edges because the edge extends transverse to its direction of movement.

The cylindrical member is rotated by ground or road contact. The slicers, protruding beyond the hoes, impact and cut on lines into the road surface to form strips, and the hoes, acting against the ground, chop the cut strips into small pieces. The irregular surface of the rings, that form the surface of the cylindrical member, carry the larger pieces of road material against the face of the grader blade and fill the pocket formed by the cylindrical memher and the blade. The material in this pocket is churned and broken by the irregular ring surfaces, and the larger pieces of material are carried against the fingers between the rings, one finger between contiguous rings, while the smaller pieces sift down thru the larger to the road bed. These fingers act as stationary grinding plates with respect to the rotating rings to further grind and break down the larger pieces of material. Also, they act to retain the material .in the pocket until it is sized to pass between the fingers and the rings or down thru the material in the pocket. While the attachment breaks and grinds the surface material, it, also, due to its weight carried on the sharp edges of the rings teeth, impacts, penetrates and compacts the subsurface material of the ground. When the blade and its attachment are angled to the direction of travel of the grader, and penetration of the teeth limited by blade height adjustment, the slicing edges act to plane a road surface; they act as a plurality of knife, scraper, or plane blades. Each edge takes a small bite, or shaving, as it contacts the road surface and as the member rotates.

A device constructed in accordance with the above outline is hereinafter described in detail and shown in the accompanying drawings, in which:

FIGURE 1 is an oblique view of the attachment secured to a road scraper blade, shown in phantom with its hanger arms broken off, with parts of the attachments frame broken away, and with many of the rings and two sets of wiper fingers eliminated from the showing.

FIGURE 2 is an oblique view of the arbor alone with parts broken away to show the stub shaft construction.

FIGURE 3 is an oblique view of a set of four wiper fingers.

FIGURE 4 is an end view of the near end of FIGURE 1 without the scraper blade.

FIGURE 5 is a detailed elevational view of an end portion of the arbor and two rings thereon in quarter section, and a portion of a wiper finger between such rings.

FIGURE 6 is a half sectional view of only the ring on the line 66 of FIGURE 5.

7 3 FIGURE 7 is an oblique extended view of one of the ring clamping lugs and its cap screw that holds the rings on the arbor.

FIGURE 8 is an oblique view of a modifiication of a wiper finger broken away from a set thereof.

FIGURE 1 is an oblique view of the device of the present invention shown in combination with blade 11 of a road grader, the blade and its support arms 12, or hangers, being shown in phantom. Other details of the grader are not shown as they vary from make to make and are not involved in the present invention as is the 4 welded thereto and to the plates. This front angle 32 must be easily removable so that when the rotor assembly is in position in the frame, wiper arm assemblies 37, four in number, may be positioned above the rotor assembly be-' fore the front angle is bolted in place. Each of these wiper arm assemblies has a base plate 38 that fits snugly between the downturned flanges of the two angles 32, 33 and blade 11 in that it both supports the present attachment 7 in working position and cooperates with the attachment in its work, as will be hereinafter described. The blade is practically uniform to all makes of graders, at least enough so that the present attachment is useable with most of them with but minor changes in the attaching means. In most graders, the blade can be pivoted about a vertical axis, a horizontal axis longitudinal of the machine, and about the axis parallel to and adjacent to the blade; and the blade may be moved longitudinally thereof.

The attachment device of the present invention has a rotor assembly 13 that is rotatable driven by contact with the road surface and materials by the advance of the grader thereover. The rotor assembly 13 is held fixed for rotation relative to the blade 11 by a frame assembly 14 which includes means for clamping the frame to the blade 11. a

The rotor comprises a tubular arbor 16 about six feet in length and 10 inches in outside diameter, and keyed to and coaxial of the arbor are seventeen rings, each ring 17 having its periphery patterned in a particular manner to effectively achieve the desired functioning of the device. Each of the rings weighs about 75 pounds, the arbor weighs about 700 pounds, and the frame about 650 pounds to give a total weight of about 2600 pounds. These weightsare given as an aid in understanding the functioning of the device.

The arbor 16 has secured to its face four splines, or keys, that extend lengthwise thereof and are equally spaced circumferentially thereof. Each of the keys 18 has a half round cross section and is laid on and secured to the face of the arbor with the round outward and so that from end to end of the arbor it spirals around the arbor an eighth of the circumference of the arbor. Each of the rings 17 is formed with keyways 19 to fit these keys 18. The rings 17 and keyways '19 are sized to easily slide onto the arbor from either end thereof. The rings 17 are held from axial movement on the arbor by a set of four lugs equally spaced at each end of the arbor. Each of these lugs 21 is U-shaped with a short and a long leg and a bolt hole 22 in the base thereof. A cap screw 23 holds each of the lugs to the end of the arbor where each is threaded therein inward of an end of one of the splines 18 with the long leg bearing against a portion of the outside ring and the short leg against the end of the arbor. A stub shaft 24 is secured in each end of the arbor 16 by securing and centering each shaft in a pair of spaced annuluses 26 secured inside of and adjacent each'end of the arbor. A journal on the outboard end of each shaft is carried in a heavy duty tapered roller bearing 27 that is bolted to the inner face of an end plate 31 of the frame assembly 14.

The frame assembly 14 is elongated in the axial direction of the rotor assembly 13, and at each end thereof it has one of the end plates 31 that has secured to it one of the arbor bearings 27. These end plates are held and tied together by a pair of top positioned wiper support angles, 32, 33. The top positioned angles are spaced slightly apart, have coplanar flanges and downturned flanges, and the rear one 33, the one to the right in the views, is welded to the end plates. The forward angle 32 is readily removable by being bolted to an open box 36, or gusset member, one of which is secured to each of the end plates inside of the angles and so that the rear angle 33 can be against the lower sides of the two coplanar flanges of the angles. Each base plate is secured to the flanges by a pair of spaced apart bolts 39 that pass thru the base plate and the space between the angles. A washer and a nut is placed on each of the bolts to'bear on the upper faces of the coplanar flanges of the angles to secure bolts and base plates and wiper assemblies in place. Each of the base plates has secured to its lower face four spaced apart arms. Each of these arms 40 is in the form of a rectangular plate which has one end thereof secured to the base plate so that the arm is normal to the base with its sides parallel to the side plates 31 of the frame assembly, and the other end, the free end, is formed with a cut 41 therein that is medialof the arm, normal to thebase, and from face to face. The cut extends about half way of the arm from its free end. This forms two fingers 42, 43 which are bent in opposite directions, splayed, away from the plane of the upper end of the arm. These wiper arms cooperate with the arbor rings 17 in a manner to be later described. There are four of these wiper arm assemblies and a wiper arm extends between portions of each of the rings 17.

Further details of the frame include the means for securing, attaching, the frame to the blade of a road grader. Inasmuch as there is some variation in blade construction between the graders of various manufacturers, the attaching means should be useable with as many types of blades as possible. Further, these scraper blades wear so that their width is lessened by long service. A generally universal mounting means is had by clamping the frame to the blade. This is accomplished by securing to the rear edge of each of the side plates an upper 44 and a lower 45 clamp fixture. The upper clamp fixture includes a bolt block that has a pair of spaced apart and opposed in registry cheeks 47 between which is slidable a back edge portion of one of the end plates 31. The cheeks are joined by a bolt sleeve 48 axially parallel to the back edge of the end plate. Each of the bolt block cheeks is provided with six transverse holes 49 which are in alignment with the six holes of the other cheek. The end plate is provided adjacent its back and top edges with six holes which will align with the cheek holes, so that the bolt block may bemoved along the rear edge of the plate once or twice the spacing between the bolt holes and may be moved out from the rear edge once the spacing of the holes, if only two bolts are used in the.

block and the frame to overhang and hook behind the top edge ofthe blade 11.

The lower clamp fixture 45 is provided with a bolt block similar to that of the upper bolt block. The lower bolt block has opposed spaced apart in registry cheeks 53 with transverse bolt holes 54 therethru in registry from one check to the other and a bolt sleeve 56 parallel to the rear edge of the end plate 31. The four bolt holes allow the block to be moved rearward the spacing of the bolt holes to adjust the position of the device with respect to the grader blade and to accommodate different types of blades. The lower end of the block is provided on its insid'e'and outside edges with a flange 57, or shoe,

with bolt holes therethru, one on each side of the block can be adjusted rearwardly by movement of the bolt block and by movement of the step with respect to the block. Also, the step has a slot therethni for the passage of a heavy lower clamp bolt 62 that also passes thru the sleeve 56 of the block. This bolt has on its lower end a square washer 63 to bridge its slot in the step. Spaced from the block, the step is upwardly turned, and this upturned portion 64 has threaded therein and therethru a set screw 66 that may be forced against the back of the blade 11 to hold the front face against a step tie bar 67 that is welded at each end thereof to one of the steps 59 and extends therebetween from end to end of the device. The bar 67 is slanted rearward so that the lower edge of the blade 11 will hook under the bar.

Each of the rings has a configuration that enables the device to do a variety of functions, all of which contribute to the achievement of the objects of the invention. These features enable the device when used for working new or old road material to cut, crush, grind, size, stratify or mix, and compact such material. It may, also, be used for planing or shaving a road surface. To accomplish these results, the attachment has been made as heavy as possible and still have operable the hydraulic and/or mechanical control means for blade adjustment and maneuvering. Each of the rings can easily have its weight increased by adding material to its sides adjacent its axial opening and between the spacing ears 71 that project from each side of the ring at each of the keyways 19. These keyways are formed in these ears and the body of the ring. Further, the inside of the ring has been angularly and radially relieved as shown in FIGURES 5 and 6. The periphery of the disc has been provided with a first series of cutter teeth and second and third series of hoe teeth. The cutter teeth are in the form of a series of circumferentially spaced, semi-circular cutter scallops 72. Each of the scallops is wedge shaped in axial cross section, is centered axially of the ring, and has an outer edge that is semi-circular or curved in profile as viewed from the axial end of the ring and the arbor. Each of the rings has been shown as provided with eight of these scallops, slicers. Medially between each of the slicers 72 is a wedge shaped hoe 73, forming the second series of teeth, or crushers, and centered on each of the slicers is another hoe 74 forming the third series of teeth that can be called an interrupted hoe because it is intersected by such slicer. All of the hoes have sides which are in common diametrical planes, normal to the ring axis. The outer radial ends of the hoes, formed by the intersection of the faces, are straight edges parallel to and all at the same radial distance from the axis of the ring, and extending between the plane diametral sides. The outer edges of the hoes are inside of the extreme outer edges of the slicers 72. The side profiles of the teeth are symmetrical about radii of the ring. An example of the dimensions of a ring are given, in inches, to aid in understanding the relationship and functioning of its parts. The arbor opening is the distance between the ends of two axially opposed ears is 4 /2; the distance between the sides of the wedges is 2 /2; the faces of the wedges intersect at radii of 6% and 9 /2; and each slicer profile has a radius of 2 centered on a ring radius of 8 71 It should be noted that in the preferred embodiment. a circle subscribed about the tip ends of the scallop teeth has an outside diameter of 21 inches, and eight circumferentially spaced scallop teeth are included in a series. The radial thickness of the ring is 5 inches. This is less than the radius of the arbor opening. It should be remembered that in the functioning of the present invention, reliance is placed upon the impact of each of the spaced, large, sharpened scallop teeth, and not upon a continuous down pressure alone as in the prior art devices wherein a large number of closely spaced small teeth are provided which afford little or no impact as would a continuous circle. The tooth spacing is significant because it may be used to determine the ability of a given scallop 6 tooth arrangement (number and outside diameter) to perform its function by impact.

FIGURE 8 is an oblique view showing a modification of a wiper arm cut away from its base. One of these wiper arms may be substituted for each of the arms shown in the wiper arm assembly of FIGURE 3, and for all the wiper arms in the attachment device. Each of these modified wiper arms is composed of a plate that is the same as any of the wiper arms 40 of FIGURE 3 but without the cut 41 which gives the fingers 42, 43. Each side of the arm 140 is formed with or has secured thereto and on each side thereof a plurality of spaced apart parallel ribs 141. These ribs are angled downwardly, that is toward the axis of the arbor when assembled in the device, from rear to front of the device. This means that material carried by the rings adjacent the arm against the arm and its ribs, in the direction of the arrow 142, will, when its strikes the ribs 141, be deflected centripitally of the rings to enhance the grinding action of the device by retaining the material in the pocket between the rings and the scraper blade and by comminuting it between the side edges of the hoe wedges and the edges of the ribs of the arms. The fingers 42, 43 illustrated in FIGURE 3 and elsewhere, may be regarded as ribs on the arms 40, and that all the ribs 42, 43, and 141 of FIGURE 8, are similar in shape and function to block material from passing between adjacent rings and in being reactors against which the rings grind.

The various parts of the attachment are easily assembled. The rings 17 slide on to the arbor 16 from either end and are locked in position by the keys 18 along the arbor and the lugs 21 at each end thereof that are tightened against the outside ears 71 of the end rings 17 to force all the rings together at their ear 71 ends. The bearings 27 are placed on the arbor stub shafts 24, and the rotor assembly 13 is ready to be placed in the frame 14 Where the bearings are bolted to the end plates 31 to secure the rotor assembly in the frame. The four wiper arm assemblies are then placed in position on the rear frame angle 33, the front angle 32 is then bolted in place and the wiper assemblies bolted up. The attachment is then ready to be secured to the grader blade.

The hereindisclosed attachment is easily secured to and in front of a road graders blade. The attachment may be laid on the ground and the grader maneuvered to be in position over the attachment with the front face of the blade 11 parallel to the attachment. The fact that the blade of a grader may be easily raised and lowered and pivoted on vertical and horizontal axes aids in easily 0btaining such alignment. The blades lower edge is set on the steps 59 in back of and contiguous the lower tie bar 67, the top clamp hooks 52 are placed on and behind the upper edge of the blade, and the top clamp bolt 51 is tightened. To obtain proper alignment of the attachment and the blade, it may be necessary to adjust, or move, the upper 44 and the lower 45 clamping bolt blocks with respect to the end plates 31 of the frame 14, and to adjust the steps 59. When the blade is secure in the clamps, the set screws 66 at the rear of the steps may be tightened to hold the blade edge securely against the tie bar 67. Once the attachment is secured to the blade, lifting and maneuvering the blade will carry the attachment with it.

Generally, the combination is operated with the blade and rotor axis normal to the direction of travel of the grader or at an angle other than ninety degrees thereto. For breaking up the surface of an oil road and for compacting a road, the axis is probably best set normal to the direction of travel. If it is desired to windrow, mix and blend, or shave the road surface, it is probably best to set the axis at an angle to the travel, the degree of angle being judged by observation of the conditions of the material before and after working it with the combination.

' road, each slicer 72 hits and slices into the road surface as the grader travels over the road and the weight of the attachment and blade is carried on these slicers. The impact of each slicer 72, in conjunction with the down pressure thereof is the operative force. Each slicer is circumferentially offset from the ones of its adjacent rings because of the slight spiral given to the keys 18 between the rings and the arbor. This prevents an axial row of the slicers impinging all at onceand circumvents the momentarily great impact loads to the rig that would inherently follow by spreading the impact of the various slices throughout one rotational cycle of the device. These slicers cut the road surface into ribbons which are broken into small pieces by the edges of the hoes 73, 74 as the slicer edges impact and enter the road surface so that the hoes can contact the material. The hoes are interjacent the slicers so that the slicers can act without hinderance of the hoes. It may require a second pass of the combination over the road before the slicers have penetrated sufficiently for the hoes to become effective. A slight angle of the arbor axis to the direction of travel will help to loosen the surface material. As large pieces of material are loosened from the road, they are carried by the hoes up and into the space between the attachment and the grader blade. Here their own'weight causes them to churn and grind, one piece against another and against the teeth of the rotor. Some of these pieces are carried against the wiper arms 40 and are ground, comminuted, between the edges of the arms and the side edges of the wedge shaped hoe teeth of the rotor. This raising and agitating of the material as it is being ground effects a stratification of the material as it deposits on the road surface. The fines sift down thru the coarse material to deposit on the road below the coarser pieces which form the road surface. It is not claimed that an old oil surfaced road can be remade in a single pass of the grader and its attachment, but the job can be done in fewer passes and quicker than in any other known way. The combination can be used for mixing and windrowing when new oil is added to road surface material, and the job done quicker than with the blade alone.

The combination can be used on new road beds for sizing and compacting base and surface material. This action will depend on the type of material and the manner in which the combination is used. The grinding action is the same for old or new material. This action is increased by pushing the rotor against the road, by increasing the speed of travel of the grader, and by other means to keep the space between the blade and the rotor filled with road material so that it will grind on itself and so that it is carried against the wiper arms and ground between the arms and the side edges of the wedge shaped hoes. The compacting of the material is had by the edges of the slicers and hoes, particularly the slicers, impacting and penetrating the road material and by the weight of'the combination'and even the grader bearing down on such edges.

Shaving of rough road surfaces to reduce or eliminate the roughness is done with the present device by angling its axis to the direction of travel and by adjusting the bladeheight above the road so that the slicers contact only the high spots on the road. As each slicer contacts a high point it takes a small bite or shaving therefrom. After two or three passes, the road is smoothed.

Considering the design from the standpoint of the individualrings, each of the scallops 72 has a generally semi-circular edge that acts as a slicer, a penetrator, and a device for the point application of a blow to the surface being worked. The edge is buttressed by a body which is wedge shaped in cross section and is integral with a base ring. The edge is in a plane normal to the axis of the ring, and is symmetrical about a radius of the ring so that the scallops are equally effective in either ring rotation direction. Because the edge is circular and each scallop is substantially a semicircular disc integral witha ring base it follows that regardless of which portion of the edge contacts the surface being worked, the direction of a'force in the plane of and normal to the edge at any point'thereof will be transferred thru the scallop to the ring base without the line of force leaving the scallop. This is part of the concept of buttressing the scallops so that they can deliver impact blows to material such as rocks without permitting scallop deflections that might absorb the blows without affecting the rock material. Also, because the seallop edge is circular, the probability. is increased that each contact with a hard object will be a point contact instead of a line or area contact; Additionally because the edge is circular, a point of contact on the edge is buttressed in the plane of the edge by the curve of such edge contiguous to such point of contact as well as by the sloping sides of the scallop contiguous with such contact point. Finally, the feature of the invention wherein the scallops of each ring are circumferentially spaced as disclosed, permits each scallop to be effective for the greater part of its edge lengths. 7

When utilizing the present invention for compacting with the rotor axis normal to the direction of travel of the device, the compacting ability of the scallops results from their edges being in planes normal to the rotor axis and from their shape. In this regard, the scallop shape allows the scallop to slice through and easily penetrate the material so that much of the energy transfer from each of the scallops occurs well below the ground surface.

In other words, a scallop may slice through the upper surface of material being worked and compact the subsurface. This is particularly beneficial because other types of compacters sometimes compact merely the surface of material being worked leaving a springy subsurface be.-

neath. Further, the material on the surface above the point of maximum penetration acts as a capping, shield, or reflector that confines and directs the energy transferred from a scallop downward into the ground. This prevents energy dissipation in the loose surface material without the needed compaction of surface or subsurface material. The failure of devices employing grids, sheepfoot-like projections, or blunt ended posts, to achieve the results of the present device is believed due to their failure to penetrate and impact at subsurface points.

The circumferential. spacing of the scallops may be defined with reference to the angular displacement of each tooth, 360 divided by the number of scallops. However, another method of measurement is more graphically related to the spacing of slicing teeth and their functioning. This method may be called the measurement of the designed depth of free scallop penetration. The meas urement is made by considering a semicircular scallop to have a sector cord that, when extended in both directions is tangential to the curved outer edges of the two adjacent scallops, the flanking scallops. The height of the sector cord (scallop tip to sector cord) is considered to be the designed depth of free penetration of a scallop without penetration of the adjacent scallops. If a scallop is positioned at the bottom of the ring and penetrates the ground material the above defined radial distance the next adjacent scallops are either just leaving the ground or just coming into contact with the ground surface. Fora given tip circle diameter (i.e. the diameter of a circle circumscribed from tip to tip of-the scallops about a ring), this design penetration of the scallops of a ring may be varied by changing the number of scallops, and by changing the radius of the curvature of edges of the scallops. These 7 important variables involved in the design of the scallops of a ring, are related by an equation in which the design penetration equals the products of the .versine of the tooth angle (360 divided by the number of scallops on each ring) and the difference of the tip circle radius and the radius of curvature of the scallop edge. Of course there are other factors influencing ring design such as the orientation of the breaker teeth, the width, spacing, and inside diameter of the rings. But more importantly, for a given tip circle radius, there are three important limiting factors of scallop tooth design related to penetration. First, scallop circles (i.e. a circle drawn about the center of curvature of the semicircular edge of a scallop with the radius of the circle being equal to the radius of curvature of the semicircular cutting edge) should not overlap as such limits the actual penetration. Second, the above described sector cord should not intersect the base ring because if it does, and if actual penetration equals the design penetration, the continuous base ring will be forced into the ground. And third, the radius of curvature of the scallop edges should be such that the edges of adjacent scallops are close to tangency to obtain maximum buttressing of the edges of each scallop.

These variables and limiting factors will now be considered relative to the design of the scallops and the ring as specifically dimensioned above. The scallop penetration is 2.4 inches and the radius of curvature of the scallop edge is 2.3125, which is 80% of the maximum of 2.905 inches (i.e., a radius of curvature wherein the scallop circles are tangent is the maximum). The penetration is slightly greater the the radius of curvature of the scallop edge. if this is considered to be close to an optimum design, then permissible variations in design for a tip circle diameter of 21 inches would seem to be a ring with five or eleven teeth, a variation from eight teeth of plus or minus three teeth, and with a scallop edge radius of curvature of plus or minus twenty percent from the eighty percent of maximum of the specifically disclosed example, the maximum radius being that at which adjacent scallop circles are tangent. The design penetration for eleven teeth and the maximum scallop radius of curvature of 2.30 inches would be 1.29 inches or 1.3. This design penetration of 1.3 inches would seem to be a minimum for any device regardless of whether the design includes a smaller or larger tip circle diameter.

In the disclosed embodiment, the scallop circles of the scallops 72 have a radius smaller than the maximum wherein adjacent scallop circles are tangent so that it follows that there is circumferential space between the adjacent scallops to facilitate positioning of the transverse hoe teeth 73.

The maximum scallop edge radius of curvature is related to the ring tip circle radius and the number of teeth by such scallop edge radius of curvature being equal to the product of the tip circle radius and the sine of half the scallop tooth angle divided by one plus the sine of half such angle. The scallop tooth angle is 360 divided by the number of scallop teeth.

From the above, it should be noted that the number of teeth and the scallop radius of curvature are trigonometric functions of the ring tip circle radius, and are not straight line functions.

While the design penetration depth of substantially 1.3 inches is a minimum value, the maximum value appears to be limited by the factor discussed above wherein the sector cord should not lie within or intersect the ring base for any considerable distance. This design minimum value of 1.3 inches for penetration is a limitation on the maximum number of teeth for a given tip circle diameter.

This minimum penetration of 1.3 inches is, also, a limitation on the inside diameter of the ring as the base ring should be as close to the scallops as possible, and the height of scallops should never be more than substantially their edge circle radius. This usually results in the radial thickness of the ring being substantially half or less than half the outside radius of the ring, i.e. the scallop tip circle radius.

From the above considerations of the design bases for the present device, it follows that the primary factors in setting the dimensions for a particular embodiment of the invention are: the design penetration, weight necessary for such penetration, and rigidity of structure to achieve impact.

Also, it should be noted that the instant device is intended to perform multiple purposes such as the planing of road surfaces wherein the rotor is angled to the direction of travel and the penetration is limited, the loosening, working, grinding, and mixing of road surfaces wherein penetration is maximized and the rotor is angled to the direction of travel; the grinding and breaking of rock and accretions, and the compacting of materials wherein the rotor axis is normal to the direction of travel.

The provision according to the present invention of a rigid wedged shaped scallop having its circular edge buttressed with a large mass as close to such edge as possible is advantageous in all of the multiple purposes for which the instant device may be utilized. Additionally the two series of transverse breaker wedges aid in scoring and breaking material, cooperate with the wiper arms in grinding material, and aid in buttressing the sides of the scallops.

It will thus be seen that the present device has many functions and performs them in new and better ways. Having thus described an embodiment of my invention and a modification thereof, its construction and operation, I claim:

1. A ground working device, comprising: an annular cylindrical arbor having support means at opposite ends thereof, said arbor being of uniform diameter and continuous between said support means, and a plurality of toothed ground working rings coaxially circumjacent said arbor and equally spaced therealong substantially the axial length of said arbor; the inside radius of said rings being substantially that of the outside radius of said arbor, and the radial thickness of said rings, including said teeth, being less than the outside radius of said arbor, and means formed with said arbor and rings for securing said rings to said arbor comprising keyways and helically extending keys.

2. A ground-material working ring for a combination scarifier and compactor, said ring being adapted for direct coaxial mounting on an arbor, comprising: an annular ring base having lateral sides, and two series of peripherally contiguous wedge shape edged teeth having their wedgeshaped bases at and integral with and positioned about said ring, each of said teeth having its lateral profile symmetrical of a ring radius; the first series of teeth being in the form of circumferentially spaced scallops having curved planar edges with the plane of each such edge normal to the axis of said base ring, said scallops being circumferentially spaced so that only one scallop at a time makes substantial contact with a surface being worked at the point of deepest penetration of said one scallop, the second series of teeth having edges transverse said edge planes and positioned radially inwardly of said first series and each tooth of said second series of teeth being located between, separating, and contiguous with a pair of teeth of said first series.

3. The combination of claim 2 in which said teeth of said second series are of a width axially of said ring substantially that of the axial width of said ring base.

4. The combination of claim 2 in which said two series of teeth are between the lateral sides of said ring base.

5. The combination of claim 2 in which said ring base is formed with spaced apart axially extending ears that serve to space apart such rings when in axial adjacency.

6. The combination of claim 2 in which the inside radius of said ring is greater than the radial thickness of said base ring and teeth.

7. The combination of claim 6 having therewith a third series of teeth equal in number to the teeth of said second series and like such second series teeth but for each tooth of said third series being peripherally centered on and axially interrupted by a tooth of said first series.

8. The combination of claim 7 in which the teeth of said second and third series are contiguous one to the next.

1 1 9. The combination of claim 8 in which the edge of each tooth of the first series is circular, and in which the edge of each tooth of the second and. third series is straight.

10. The combination of a plurality of rings such'as the ring of claim 9 and interjacent said rings an annular cylindrical arbor having an outside radius substantially that of the inside radius of said rings, and means directly securing each of said rings coaxially of, around, and to said arbor.

11. The combination of claim 10 inwhich said means includes forming said base rings interiorly with axially extending keyways, and helically extending keys secured to the outside of said arbor and lying in said keyways.

12. The combination of claim 11 in which each of said base rings is formed with spaced apart axially extending ears that serve to space apart said rings and said ears being formed with portions of said keyways.

1 2 References Cited UNITED STATES PATENTS 260,342 6/ 1382 Williamson 172-547 730,837 6/1903 Nichols 172554 7 1,178,515 5/1916 Haldin' 172549 2,146,222 2/1939 Pace 172540 X 3,136,078 6/1964 Renault 37-146 FOREIGN PATENTS 31,188 4/1885 Germany. 539,149 8/1941 Great Britain.

ABRAHAM G. STONE, Primary Examiner.

15 WILLIAM A. SMITH III, Examiner.

R. L. HOLLISTER, Assistant Examiner. 

1. A GROUND WORKING DEVICE, COMPRISING: AN ANNULAR CYLINDRICAL ARBOR HAVING SUPPORT MEANS AT OPPOSITE ENDS THEREOF, SAID ARBOR BEING OF UNIFORM DIAMETER AND CONTINUOUS BETWEEN SAID SUPPORT MEANS, AND A PLURALITY OF TOOTHED GROUND WORKING RINGS COAXIALLY CIRCUMJACENT SAID ARBOR AND EQUALLY SPACED THEREALONG SUBSTANTIALLY THE AXIAL LENGTH OF SAID ARBOR; THE INSIDE RADIUS OF SAID RINGS BEING SUBSTANTIALLY THAT OF THE OUTSIDE RADIUS OF SAID ARBOR, AND THE RADIAL THICKNESS OF SAID RINGS, INCLUDING SAID TEETH, BEING LESS THAN THE OUTSIDE RADIUS OF SAID ARBOR, AND MEANS FORMED WITH SAID ARBOR AND RINGS FOR SECURING SAID RINGS TO SAID ARBOR COMPRISING KEYWAYS AND HELICALLY EXTENDING KEYS. 